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15 October 2008

Bad to The Bone! Pt 1

As many of you know, Andy Holden has been building an awesome Sagaris Bodied Tuscan over the last two years or so and you may have seen pics on the PH / TVRCC Forums. It can clearly be seen that this is a truly magnificent job, with all areas upgraded and developed for Endurance racing in the UK and Europe. What isn’t evident in the pics and posts is just how much work Andy has done and how far down the line he went. All the way!

Andy has taken some very valuable spare time (he doesn’t get much as you will see) to give us an insight into the build and development of this now Sagaris GT3 car.

Part two will be in two weeks on the shake down session at Silverstone. Enjoy!


I wanted to (as far as I can) guarantee reliability.  So I didn't go down the crate engine then modify route - I started with an ex Mosler engine (5.7 LS2) that had already had the head work done, was already dry-sumped (the sump pan is a work of art - 1" deep, amazing thing), and had the front end already in place (water and oil pumps).  It’s a tried and tested package - my engine powered the Eclipse Mosler through a Britcar 24, was rebuilt afterwards and has not been used since.

I took the same approach on the clutch etc.  I was worried about getting the gearbox perfectly aligned with the crank and ensuring the starter and clutch was man enough for the job.  So I went for a Tilton driveline package specifically designed for the LS engine.  Magnesium bell-housing, Tilton super starter, 5.5" triple plate race clutch and flywheel.  I had to move a chassis tube to accommodate the starter - which was a bit of a wrench - I really didn't want to chop the chassis but had no choice.

For gearbox, initially I was going to have a Hewland sequential box as 1) they won Le Mans in the Panoz (and were in the T440Rs) and 2) they are 20 mins down the road from me.  They did me a mock up housing but it was just too wide to fit in the chassis.  It was a shame - the Hewland guys were really helpful, I had the full factory tour and two or three meetings with one of the Directors and they happily sent me off with a £3,000 casting to do a trial fit.

X Trac was another option as they are 20 mins in the opposite direction.  However when someone doesn't answer your calls when you have £14,000 to spend on a gearbox, I asked myself how quick would they be to sort an issue if it arose once I had parted with the money.

So I ended up with what was probably the best option anyway, the latest Hollinger 6 speed sequential as now fitted to the Aussie V8 Super cars, rated for 650 ft lb of torque for endurance racing.  Weighs just 38kg (almost exactly the same as a T5), has a removable input shaft and an integral oil cooler pump.  I also opted for a flat shift lever (up shifts are clutch less anyway, but they are also now full throttle) and temperature sensor.  This had to be ordered from Australia as the European distributor had clearly attended the same customer service school as the X Trac people.  The Aussies were great, if a little stressed from overwork.  Unfortunately the exchange rate worked against me post order, but “C'est la vie”.

I had to have an adaptor plate fabricated to my design to adapt the Hollinger bolt pattern to the LS bell housing.  This also forms the rear engine mount.  Both box and engine are solid mounted to the chassis; all mounts and brackets were fabricated to suit.

Positioning the engine was a nightmare.  Although it seemed like there was plenty of room, there is only a few mm of clearance in all directions.  Any lower and the oil pump hit a tube.  Left or right and the oil pump foul the steering column or the gearbox hits a tube.  Forward or back and the starter or oil pump hits.  Could only commit to welding the mounts in once we had the gearbox and bell housing on the back of the engine and put the whole shooting match in the hole.

The engine always ran on a Motec ECU - it is arguably the best available so that is what I went with.  I needed a new engine and ECU loom, and frankly the old TVR loom was a bit crap and a failure waiting to happen.  Wires that are bent over them because they are too long will fail, and Sods Law dictates it will fail just before qualifying at Spa and you will never find it because it is buried deep in the loom.  So I had a bespoke motorsport spec loom made for the car at the same time.  To be honest, with new wiring required for the gearbox and diff temp probes, the GPS receiver, radio, electronic fire extinguisher, electric diff pump, flat shift, pit lane limiter etc... The thing would have been a bloody mess if I had tried to stick with the old loom.

The loom is now modular, so the central control panel can now be unplugged in its entirety if we ever have a wiring issue.  The control panel contains all the relays, switches and pop fuses.  On the Tuscan these were scattered around the car and most are hidden in the fuel bay where access is a complete nightmare.

Since we were doing a complete rewire we added a few bits and pieces.... changed to a Motec dash and shift light module controlled by a CAN bus system.  Lap timing and track plotting done by GPS with a virtual beacon established at each circuit by pressing a button on the steering wheel.  No infrared beacons anymore...  We also have a pit lane speed limiter button, push to talk for the radio, headlamp flash (which works with lights on or off) and the usual scroll and alarm cancel function, all steering wheel buttons.

 We have a dial to switch between 4 different maps - a full bore race map, safety car setting (conserve fuel), wet setting (everything turned down) and a restricted setting which we will only set up if we want to run the car somewhere that requires us to run an air restrictor.

Transmission temps are critical so we now monitor and log them.  The ECU switches the diff pump on and off according to temp.  The diff pump is a lovely little unit I sourced from the USA - used for pumping oil to turbos on Harley drag bikes.  Brass helical gears - very nice.  I consulted with the ex TVR GT programme engineers who now work for Shorty at Mosler Europe and as a result put the diff cooler at the front of the car in the airflow.  No matter where they put the diff cooler on the T400 at the rear of the car, diff temps were an issue until they moved it to the front.

Prop shaft is bespoke and we have a new 3.08 diff - tapped for the oil pick up and return.  The diff remains mounted on bushes, and thanks to Tim's initial experience, has an additional bracket across the rear that picks up into the bottom of the rear cover.  This 'should' stop the diff trying to rotate rather than the wheels when the power goes down, but we'll have to see what happens in testing.

What else.... 70 litre fuel cell was too small, so I had a 117 litre ATL cell with FIA safety bladder custom made to fit in the passenger bay.  The nice thing about this (apart from the safety aspect) is that it has internal pumps, filters and collector.  Tim had a devil of a job to plumb in a low-pressure pump, filter, collector and high pressure pump into a tiny space in the passenger foot well - we just have a fuel pick up and return straight onto the top plate of the cell.  We don't need a low-pressure pump, but we specced two high-pressure pumps so that if one fails mid race we just switch to the back up pump.  We have the same dry break filler equipment, but we now also have a dry break on the fuel rail to which we can attach a hose to pump out fuel and drain the tank.

Back in the engine bay, the engine sits slightly lower and further back than Tim's.  Initially we all had the same exhausts made from AJP manifolds, but because my engine sits lower they had to be remade.  Naturally we have wide band lambda.

To improve heat management I removed the front bulkhead on the passenger side and remade it so that the dry sump oil tank now sits in the engine bay rather than inside the car.  I wish I had done that all along - don't know why I copied the Tuscan in that respect, this makes far more sense.  All the heat (and mess if it leaks) is where it doesn't matter.

I had a few little issues to deal with - had to raise the steering rack 2 inches.  The alternator was an issue - the Mosler one is huge and was never going to fit.  Now have a very small Brise version mounted top left on a fabricated bracket, with a serpentine belt arrangement that also drives the water pump.

Rad frame is a more substantial design - last year's version bent in use.  The rad ducting is now 13mm honeycomb to help dissipate energy in an impact.  Air filter is the same as the Racesport car.  The engine came with Kinsler throttle bodies which we hoped to retain, but the engine is tucked up under the windscreen scuttle so that put paid to that.  It was therefore more expense to get a FAST LSx intake and 90mm throttle body.

Aero wise I started playing around with 13mm ali faced honeycomb and the floors and splitter are now made from the stuff.  The splitter has a protective carbon kevlar covering on the underside and small venturis to carry air to the brakes.  All this required epoxy resins and aerospace glues for the steel hard points for critical mounting points.  The floor is now a continuous flat section from the splitter all the way to the rear diffuser, which has tow additional carbon strakes to improve airflow.  The splitter is much stiffer and lighter than the plywood version from last year. We also have carbon dive planes made in-house.

So, all in all it’s been something of a marathon.  I had delays and problems along the way - I was late ordering the gearbox because I was initially going to have the Hewland.  By the time I ordered the Hollinger they were outfitting the whole Aussie V8 grid plus had won the contract for the Porsche 997 sequential boxes - they're only a small company so were a bit swamped.   The wiring man added a few more delays and didn't get everything right first time.  And right up until yesterday we were struggling with config problems with the ECU and crank/cam sensors.  Once sorted though the thing roared into life.  It spins over beautifully on the starter - the little red Top 30 has no problem whizzing it over hot or cold.  Oil pressure is great, no leaks in any of the plumbing, and the gearbox pops up and down through the gears perfectly.

The only issue we had was the rear callipers fouling the discs, which seems to be a tolerance issue in manufacturing of the uprights (new this year).  We need to sort that this weekend and then back to PowerStation for mapping.

We have upped the spring rates considerably from last year and the dampers are valved very stiffly.  If we can manage the torque and keep the diff where it is supposed to be, we don't break drive shafts and stub axles, and manage the under bonnet heat, we'll have one hell of a race car.

It’s no longer a cheap car, but there is nothing of comparable cost that could get anywhere close to its performance.  We should be able to take down some of the gentlemen drivers in the Mosler - I don't think we'll catch “Fluxy” in his though.

Don't know overall weight yet as we'll do the set up work and corner weight it after the full mapping run.

Tim and I have been in contact throughout comparing ideas and it has been great to be able to bounce ideas off each other.  We copied each other on some things and went our own way on others, but the approach has always been pretty collaborative.  With Tim getting his car out first I had advanced notice of a couple of issues (silencer temps and diff mounts for example), so I have benefited quite a bit from that.

It’s been a long old haul and I haven't been in a racecar for virtually a year.  We've virtually missed the whole season, so I'm really keen to get the car on track in the next couple of weeks and see what the old (new?) girl can do.  We'll keep you posted....

Andy Holden
Team Holden Racing

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